\documentclass[]{article}
\setlength{\pdfpagewidth}{8.5in} \setlength{\pdfpageheight}{11in}
\begin{document}
\begin{tabular}{lcccc} \hline
 & (1) & (2) & (3) & (4) \\
VARIABLES & specialized\_rankfirst & specialized\_proportion & specialized\_listed & d\_enroll\_specialized \\ \hline
 &  &  &  &  \\
1.grupo\_gen & 0.00643 & 0.00658** & 0.00314 & 0.00443 \\
 & (0.0051) & (0.0031) & (0.0063) & (0.0047) \\
2.grupo\_gen & 0.00448 & 0.00162 & 0.00579 & 0.00474* \\
 & (0.0029) & (0.0017) & (0.0039) & (0.0027) \\
 &  &  &  &  \\
Observations & 39,005 & 39,005 & 39,005 & 39,005 \\
R-squared & 0.061 & 0.022 & 0.085 & 0.054 \\
 Mean of dependent variable & 0.0906 & 0.0286 & 0.172 & 0.0763 \\ \hline
\multicolumn{5}{c}{ Robust standard errors in parentheses} \\
\multicolumn{5}{c}{ *** p$<$0.01, ** p$<$0.05, * p$<$0.1} \\
\end{tabular}
\end{document}
